The field of the invention is that of antenna systems, in particular for pointing at non-geostationary satellites. To be more precise, the present invention concerns a system with at least two antennas capable of pointing independently of each other in any direction within a solid angle.
In the context of the present invention, a terrestrial transmission system is considered, e.g. as installed on the roof of a building. The system includes at least two antennas, for example parabolic antennas, designed to communicate with, i.e. to transmit to and/or receive from, non-geostationary satellites. The antennas are close together (i.e. co-located) for reasons of overall size and/or to reduce the lengths of the connections to a single modem and/or so that they can be located under the same protective radome. The two antennas can be steered independently of each other in azimuth and in elevation, i.e. each is mounted on a separate support.
The problem that arises with a system of the above kind is that one antenna may mask the other antenna(s), as shown in FIGS. 1 and 2, because of the position of the satellites, and in particular when their elevation is low. The antennas are considered to be located in the same horizontal plane, i.e. at the same height.
In FIG. 1, which is a simplified plan view of a system with two co-located parabolic antennas, the two antennas 10 and 11 are pointing in opposite directions and neither of them can transmit or receive signals because they mask each other. In FIG. 2, the antennas 10 and 11 are pointing in the same direction and the antenna 11 is therefore masking the antenna 10.
To avoid such masking, it is possible to move the antennas a greater distance apart, the requirements for compactness are then no longer satisfied. Also, it is no longer possible to protect them by a common radome.
One object of the present invention is to remedy the above drawbacks.